import math
a,b,c,d = map(float,input().split())
x = abs(c-a)
y = abs(d-b)
S = (x**2+y**2)**0.5
print(S) import math math a,b,c,d = map(float,input().split()) a map(float,input().split()) map float input().split() ().split () input split b c d x = abs(c-a) x abs(c-a) abs c-a c a y = abs(d-b) y abs(d-b) abs d-b d b S = (x**2+y**2)**0.5 S (x**2+y**2)**0.5 x**2+y**2 x**2 x 2 y**2 y 2 0.5 print(S) print S d = map(float,input().split()) map(float,input().split()) d c,d = map(float,input().split()) map(float,input().split()) c a,b,c,d = map(float,input().split()) map(float,input().split()) a b,c,d = map(float,input().split()) map(float,input().split()) b x = abs(c-a) abs(c-a) x y = abs(d-b) abs(d-b) y S = (x**2+y**2)**0.5 (x**2+y**2)**0.5 S
import math
a,b,c,d = map(float,input().split())
x = abs(c-a)
y = abs(d-b)
S = (x**2+y**2)**0.5
print(S)
